Rotary gas compressor



Npv. 11', 1952 F. H. BEALL ROTARY GAS COMPRESSOR 2 SHEETS-SHEET 1 Filed May 6, 1947 l/IIIIIIIIIIIIIII I Q i l Nov. 11, 1952 F. H. BEALL ROTARY GAS COMPRESSOR Filed May 6, 1947 2 SHEETSSHEET 2 Patented Nov. 11 1952 cUNITED STATES PATENT OFFICE ROTARY GAS COMPRESSOR 7 Frank H. Bealrbetroit, Mich.; Lois Viola Brown BeaIL'executrix of Frank H. Bcall, deceased, assignor to Lois Viola. Brown Beall, Detroit,

Mich.

Application May 6, 1947, Serial No. 746,417

until 'the efficiency of the ordinary household 7 refrigerator compressors isvery low.

The primary object of this invention is to provide an efiicient, self lubricating unit containing an oil storage compartment which will'contain sufficient lubricant for maintaining proper lubrication over a period of years.

In accordance with my invention I provide a hollow cylindrical rotor provided with a plurality of nozzles for ejecting a limited quantity of oil or other operating fluid per revolution into an annular space extending substantially about twothirds around the circumference of the rotor.

The refrigerating gas enters one side of this annular space and is carried around the rotor by the oil entering this space through the nozzles in the rotor and which is exhausted at the opposite side of the annular space into an expansion passage where the velocity of'the operating fluid is utilized to compress the refrigerating gas to the desired pressure.

. A further object of the invention is to provide proper seals so that, when inoperative, leakage is prevented from taking place from the high pressure to the low pressure side of the refrigerating Further objects of the invention will appear in the hereinafter description of a preferred embodiment of the invention. q

The invention consists innovel parts and combination of parts to be described hereinafter, all of which contribute to produce an'efiicient refrigerating pump.

In the drawing: I

Fig. 1 is a vertical section of mycompressor taken on line ll of Fig.2.]

Fig-2 is a cross section taken on line 2--2 of Fig.1. I

Fig. 3 is a crosssection taken on line 3-3 of Fig. 1.

Fig. 4 is a diagrammatic showing of the intercooler system for the compressor system shown in Figs. 1 and 2. g 1 1 Fig. 5 is avertical section of an alternative design of my compressor "taken on line-5- 5 of Fig. 6.

Fig. 6 is a cross section taken on line 6--6 of Fig. 5.

Fig. '7 is a diagrammatic showing of the intercooler system for the alternative design of my compressor shown in Figs. 5 and 6.

Fig. 8 is a cross section of a third form of my compressor system.

In the compression of refrigerating gases by present methods, such as using the piston and cylinder, little heat-is lost in the compression cycle and the compression takes place according to the adiabatic equation PV zconstant- PcVc =PiVi PiVi Pc= Giving PCIPZ'VV Where Pizthe absolute initial pressure Pc the absolute final pressure vizthe initial volume Vc the volume at completion of the stroke V=the volumetric compression ratio y=the exponent Using a compression ratio of 5, P0 14 and =119,1bs. absolute :104 lbs. gauge In contrast with theadiabatic compression, an isothermal compression would follow the following equationi Thus for the same final pressure and volume the ratio of initial volumes are A second important advantage of isothermal compression over adiabatic compression is the temperature of the gases at the beginning of the compression stroke. Where adiabatic compression is used the cylinder becomes highly heated and as a result the incoming gases during the intake stroke of the piston become heated before the compression stroke commences. In compressors a temperature of 125 to 150 F. is not uncommon at the beginning of the compression stroke. The equation for the temperature at the completion of the compression stroke is as follows:

Thus using the above experimentally determined value of y:l.33 this becomes:

where To and Ti are temperatures above absolute zero. Thus using 135 F. as the initial temperature and V= the equation becomes:

It is this temperature at the completion of the compression stroke that producesthe 125 to 150 F. temperature at the beginning of the compression stroke. Incomparison with this temperature at the completion of the compression stroke the temperature at the completion of the compression stroke of the isothermal compression isthe sameas the initial temperature, say about '75 to 80 F. V H H 7 Since the weight of gas per unit volume varies as the absolute temperature the ratio of the weight of gases per unit volume becomes:

Thus the resultant advantage of the use of isothermal compression as against adiabatic compression for temperatures and pressures normal to refrigerating cycles is expressed by the following equation:

While applicants process does not produce complete isothermal compression the tremendous advantage of using a compressive medium that fiows through an intercooler between compression strokes is obvious.

In the figures, Irepresents a casing in which is formed'a cavity2 adapted to closely fit a hollow rotor 3 with a minimum of clearance 4 between the rotor 3 and casing I throughout an arc 5 forming an upper portion of the periphery of cavity 2, and with a compressor clearance volume 6 between the casing I and rotor 3 throughout the remainder of the periphery of the cavity. Clearance B'is greater on one side of the arc of minimum clearance as indicated at I and gradually decreases in the direction of rotation as indicated at 8 until a minimum clearance is attained just prior to the arc of minimum clearance 5.

Leading into the clearance I is the inlet port 9 for drawing in the'refrigerating gas through check valve II) from the pipe II connected with the low pressure side of the refrigerating sys-' tem.

Leading from the clearance 8 is the outlet port I2 leading into the oil separator I3.

Rotor 3 is formed of a plurality of segments I4 fastened to end pieces I5-I5 by a plurality of rods I6 whichvmay be welded as at IT. Segments I4 are so formed that abutting segments form nozzles I8 so directed as to eject the oil from the cavity I9 in the hollow rotor 3 in the direction of rotation as indicated by the arrow in Fig. 2. To retain the segments against the centrifugal force they are keyed into end pieces I5- -I5 by the circular keys I6.

In operation, rotor 3 rotates in the direction of the arrow, drawing in low pressure refrigerating gas from pipe II through check valve I0 and around clearance 6. During rotation, oil from cavity I9 is ejected into clearance 6 to form slugs 20 which increase in size during rotation and partially compress the refrigerating gas and ex pel itinto outlet port I2. v

Outlet port I2 is formed as an expanding no'zzle so that the velocity'of theoilslugs 20' gradually slow down and impart their energy to the refrigerating gases to compress them to the desired pressure. At a certain point 2| in the expanding nozzle the oil slugs disintegrate and form an oil spray 22, which through surface friction continue 'to impart their energy to the gases until the outlet port I2 leads into the oil separator I3. After separation the compressed gases pass into the high pressure side of the refrigerating system through outlet 23.

For efficient operation the nozzles I8 are so restricted that the 'oil expelled from cavity I9 into clearance 6 is limited so that the kinetic energy of the oil issuflicient to compress the gases entering from the low pressure side of the refrigerating system through inlet passage 9 to the pressure necessary on the high pressure side of the refrigerating system in oil separator I3. To prev'ent the oil from'fiowing along the walls of the expanding nozzle I2, the wall is undercut as shown so that the rapidly moving oil is injected into the gas stream. v I

Rotor 3 is mounted on stub shaft '24 journaled in casing 'I and hollow shaft 25 journal'ed in cover plate 26 which is bolted in casing I by bolts 21. Casing I is bolted tofhousing 28 by bolts 29. Formed in housing 28 adjacent casing I is an oil well or'smrage compartment 30.

Shaft 25 projectjsjnto thifs'compartrrient or reservoir and has fixed thereon'gear "3| which meshes with gear 32 which is driven by motor 33.

Housing 28 is sealed bycove'r plate 34 which is bolted to the housing by bolts 35.

Oil from the storage compartment 30 enters the rotor cavity I9 through hollow shaft 25 and passes through thech'eck valve 36 which is retained in closed position by the spring 31 "and thus through the nozzles I8, clearance 6 and expanding nozzle I2 into the oil separator I3.

From the separator the oil leavesby pipe 38 and is returned to the oil storagecompartment 30 'by means of float valve '38 so as to maintain a constant oil level 39 in oil separator I3. Pipe 38 includes an oil cooler 38' so that the oil is cooled before entering the storage compartment 30.

Oil for the motor bearings is 's'craped'fro'm the top of gear wheel 32 by scraper 39 anclifed into oil cup 40 which is connected bypipes 4| As shownin Fig. 3, the oil is retained at a constant level 5. H by vent 45 and oil is constantly fed to the bearings by oil ring 46. V

The oiling of the rotor bearing for shaft 25 results from the centrifugal force of the rotor which draws in oil from the storage compartment, along the bearing and end piece 15 and out into clearance 6. Oil is'fed to the bearing for stub shaft 24 by drilled passage 41 and to clearance 6 in the same way. Due to the very small clearances the quantity of oil so 'circulated is small, but suificient for lubricating purposes.

A feature of this invention is the seal between the high pressure and'low'pressure side of the refrigerating system. In all small refrigeratingunits, such as this system is particularly'directed, the unit is inoperative a substantial portion of the time. It is therefore'particularly important that there be no leakage through the bearing of shaft 25 in cover plate 26 into housing 28 which is connected by tube 50 to pipe ll so as to be subject to the pressure on the low pressure side of the refrigerating system.

As constructed rotor 3, when in the static condition, is subjected to the'high pressure side of the refrigerating system as represented by the gas pressure in separator l3. As a result rotor 3 will be pressed to the left, as shown in Fig. 1, due to the pressure'on the right hand side of the rotor which must be supported by the pressure on the left hand side of the rotor. The supporting area 51, however, is less than the total of th right hand area by the unsupported area of shaft 25 and therefore the hydrostatic pressure in the oil film in area 5| is greater than the difference in pressure between the high and low side of the refrigerating system and no leakage can occur through the bearing for shaft 25 when the pump is in a static condition. Due to capillary attraction the oil film is maintained in area 5! under all reasonable differential of pressure occurring in a refrigerating system.

Figs. 5 and 6 show an alternative form of the invention. The construction of my pump is the same and like parts have been given the same numbers. In this form, however, shaft 25' is solid and stub shaft 24' is hollow, as indicated at 6B, and oil from the separator l3 leaves by pipe El and enters chamber 62 and thence. through hollow shaft 24' to cavity I9 in hollow rotor 3. In this case the oil cooler BI is located in connection El and will have to be constructed to withstand the pressure of the high pressure side of the refrigeratin system. The connection 38 between the separator I3 and the oil storage compartment would still be required since there would be a small leakage of oil along shaft 25"and area 5| during pump operation.

However, no oil cooler is required inthis connection. When the pump is inoperative the seal for a return flow of this oil along shaft 5| would be complete, as explained above for Figs. 1 and 2. Oil for lubricating stub shaft 24' would come from chamber 62. Also check valve 36 "would not be required in this form ofthe. invention.

Fig. 8 shows a third alternative form'of the invention. In this form check valve I0 is omitted and a check valve 10 is added, so that the .compressed refrigerating gas from the low pressure inlet H, and the oil, passes through this valve after leaving the outlet port l2. Since the rotor 3 and clearance 6 is subject to the pressure of the low pressure side of the refrigerating sys-f tem; when the pump is not .operating, check valve--36,-- shown in Fig. 1, is not required and the 'oil enters cavity IQ of rotor 3' through hollow shaft 25 from; storage compartment 30 as shown in Fig. 1. Oil from separator I3 is conducted back to storage compartment 30 through passage 38, as shown in Figs. 1, 2 and 4, after-passing through oil cooler 38'. l 4.

What I claim is:

1. A compressor for a gaseous fluid, said compressor comprising a casing, said casin having a generally cylindrical cavity formed therein, a cylindrical rotor in said cavity, a pair of shafts mounted in bearings for supporting said rotor, oneof said shafts projecting from said casing for rotating said rotor, said rotor containing a hollow compartment, said rotor and said casing being spaced apart and forming a compressor clearance volume therebetween extending around a substantial portion of the periphery of said rotor, said casing having an inlet passage for said gaseous fiuid leading into one side of said compressor clearance volume, said casing having an outlet passage leading from the other side of said compressor clearance volume,'said cylindrical cavity being imperforate between said inlet and outlet passages, said inlet and outlet passages being separated by an arc of minimum clearance between said cylindrical rotor and said casing throughout the remaining portion of the periphery of said rotor, nozzles in said rotor connecting said hollow compartment with said compressor clearance volume and minimum clearance, a compressive fluid in said hollow compartment, a reservoir for said compressive fluid and means connecting said hollow compartment with said reservoir whereby fluid from said reservoir and hollow compartment is ejected from said nozzles and compresses said gaseous fluid as it travels around said compressor clearance volume to said outlet passage, a separator for said gaseous fluid and said compressive fluid connected to said outlet passage, said outlet passage bein of suflicient length to permit the momentum of said compressive fluid to further compress said gaseous fluid between said compressor clearance volume and said separator.

2. The combination of claim 1 further characterized whereby the area of said outlet passage increases from its connection with said compressor clearance volume to said separator.

3. The combination of claim 1 further characterized wherein the area of said compressor clearance volume decreases from said inlet side of said compressor clearance volume to the outlet side thereof.

4. The combination of claim 1 further characterized by a check valve located in said inlet passage.

5. The combination of claim 4 further characterized wherein said inlet passage decreases in area from said check valve to its junction with said compressor clearance volume.

6. The combination of claim 1 further characterized wherein said inlet passage and compressor clearance Volume decrease in area until the junction with said outlet passage and wherein said outlet passage increases in area between said junction and said separator.

7. The combination of claim 1 further characterized wherein said reservoir is associated with said separator and subject to the pressure of said gaseous fluid after compression and said connectin means connects said reservoir With said. hollow compartment, whereby the-pressure.

in said hollow compartment is substantially the, samevv as that. of said compressedgaseous fluid.

8. The combination of claim 7-: further char-v acterized, by cooling means in said connecting means.

9. The combination, of claim 7 further characterized wherein one ofsaid shafts is a hollow shaft and said connecting means includes said hollow shaft.

10.1 The combination of claim 1 further characterized wherein said reservoir is separate from, said separator and connected thereto by additional connecting means.

11. I 'he combination of claim 10 further characterized to include CGQIillg. means in said additional connecting means.

12. The combination of claim 10 further characterized by valve means in said additional connecting means to permit the flow of compressive fluid therethrough, but to maintain a higher pressure in said separator than in said reservoir.

13; A compressor unit for a gaseous fluid, said compressor unit comprising a casing, said casing having a generally cylindrical cavity, an oil Well exterior to said cavity, a cylindrical rotor in said cavity, a pair of shafts. mounted. in bearings for supporting said rotor, one of said shaftsprojecting from said casing into said oil well for rotating said rotor, said rotor containing a hollow compartment, said rotor and said. casing being spaced apart forming a compressor clearance volume therebetween extending around a substantial portion of the periphery of said rotor, said casing having any inlet passage for said gaseous fluid leading into one side of said compressor clearance volume, said casing having an outlet passage leading from the other side of said compressor clearance volume, said cylindrical cavi'ty being imperforate between said inlet and outlet passages, said inlet and outlet passages being separated by an'arc of minimum clearance between said cylindrical rotor and said casing throughout the remaining portionof the periphery of said rotor, nozzles in, said rotor connecting said hollow compartment with said compressor clearance volume and minimum clearance, a compressive fluid in said hollowcompartment, a separator for said gaseous fluid and said compressive fluid connected to said outlet passage and connecting meansbetween said separator and hollow compartment to return said comp-ressive fluid from said separator to said hollow compartment whereby fluid from said separator and hollow compartment is ejected from said nozzles and compresses said gaseous fluid as said nozzles travel around said compressor clearance volume to said outlet passage, a housing mounted on said casing, said projecting shaft projecting into said housing, said oil well being located in said housing, a gear wheel mounted on said shaft located in said oil well in said housing, and means within said housing to drive said gear wheel.

14. The combination of claim 13, further characterized by an electric motor in said housing, said motor being provided with bearings and oil means therefore and said drive means being a second gear wheel driven by said motor and means for automatically supplying oil from said oil well to said motor bearings.

15. The combination of claim 13 further characterized wherein said compressive fluid is oil and said oil well constitutes an oil reservoir-located in said connecting means between said separator and said hollowcompartment and said projecting shaft is hollow to provide the connecting means between said reservoir and saidhollow compartment.

16. The combination of claim 15 further characterized by the provision of .a checkvalve in said connecting means between said reservoir and said hollow compartment.

1'7. A compressor system for agaseous fluid, said compressor system including a high and low pressure side, comprising a'casing, said casing having a generally cylindrical cavity formed therein, a cylindrical rotor mounted for rotation in said cavity, said casing being provided with bearings at opposite endsof said cavity, a pair of shafts mounted in said bearings for supporting said rotor, one of said shafts projecting from its bearing and said casing for rotating said rotor, said rotor containing a hollow compartment, said rotor and said casingbeing formed to provide a compressor clearance volume therebetween extending around a substantial portion of the periphery of said'rotor, said casing having an inlet passage for said gaseous fluid leading into one side of said compressor clearance volume, said casing having an outlet passage leading from the other side of said compressor clearance volume, said cylindrical cavity being imperforatebetween said inlet and outlet passages, said inlet and outlet passages being separated by an arc of minimum clearance between said cylindrical rotor and said casing through-out the remaining portion of the periphery of said rotor, nozzles in said rotor connecting said hollow compartment with said compressor clearance volume and minimum clearance, a compressive fluid in said hollow compartment, a separator for said gaseous fluid and compressive fluid connected to said outlet passage and connecting means between said separator and hollow compartment to return said compressive fluid from said separator to said hollow compartment whereby fluid from said separator and hollow compartment is ejected from said nozzles and compresses said gaseous fluid as said nozzles travel around said compressor clearance volume, a check valve in said inlet passage, said shaft, projecting through said casing, being of substantially less diameter than said rotor, said rotor having a side wall extending from said projecting shaft to the perimeter of said rotor and said casing having a side wall surrounding the bearing of said projecting shaft and registering with said rotor side wall whereby the area of said registering side walls is less than the area of said registering side walls and said shaft, oiling means for said one bearing and said registering side walls whereby the resulting hydrostatic pressure in said oil film on said registering side walls isgreater than the pressure on the high pressure side of said system when said compressor is not operating, thus preventing leakage of said gaseous fluid past said bearing for said projecting shaft.

18. A compressor for a gaseous fluid, said compressor comprising a casing having a generally cylindrical cavity formed therein, a cylindrical rotor in said cavity having a hollow compartment therein containing a compressive fluid, said rotor and said casing being formed to provide a compressor clearance volume therebetween extending around a substantial portion of the periphery of said rotor, said casing having an inlet passage for said gaseous fluid leading into one side of said compressor clearance volume, said casing having an outlet passage leading from the other side of said compressor clearance volume, saidcylindrical cavity being imperforate between said inlet and outlet passages, said inlet and outlet passages being separated by an arc of minimum clearance between said cylindrical rotor and said casing throughout the remaining portion of the periphery of said rotor, nozzles in said rotor connecting said hollow compart- V ment with said compressor clearance volume and minimum clearance, a separator for said gaseous fluid and compressive fluid connected to said outlet passage and connecting means between said separator and hollow compartment whereby fluid from said separator and hollow compartment is injected from said nozzles and compresses said gaseous fluid as said nozzles travel around saidcompressor clearance volume, a check valve in said outlet passage and valve means in said connecting means to permit the flow of compressive fluid therethrough, but adapted to maintain a higher pressure in said separator than in said hollow chamber when said rotor is inoperative.

of the periphery of said rotor, said casing having an inlet passage for said gaseous fluid leading into one side of said compressor clearance volume, said casing having an outlet passage leading from: the other side of said compressor clearance volume, said cylindrical cavity being imperforate between said inlet and outlet passages, said inlet and outlet passages being separated by an arc '20 19.; A compressor for a gaseous fluid, said comof minimum clearance between said cylindrical rotor and said casing throughout the remaining portion of the periphery of said rotor, nozzles in said rotor connecting said hollow compartment with said compressor clearance volume and minimum clearance, a compressive fluid in said hollow compartment, a reservoir for said compressive fluid and means connecting said reservoir and said hollow compartment, whereby said compressive fluid from said reservoir and hollow compartment is, ejected from said nozzles and compresses said gaseous fluid as it travels around said compressor clearance volume to said outlet passage and a separator for said gaseous fluid and said compressive fluid connected to said outlet passage.

20. The combination of claim 19 further characterized wherein said reservoir is associated with said separator and said nonprojecting shaft is hollow and said connecting means includes said hollow shaft.

FRANK H. BEALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 30 1,060,935 Petermoller May 6, 1913 1,115,942 Kieser Nov. 3, 1914 1,280,276 Morse Oct. 1, 1918 FOREIGN PATENTS Number Country Date 104,645 Austria June 15, 1926 287,448 Great Britain May 24, 1928 

